Top feed mechanism for sewing machines



Feb. 22, 1938. c. w. MUELLER TOP FEED MECHANISM FOR SEWING MACHINES Filed March 24, 1937 u I A Patented Feb. 22, 1938 TOP FEED MECHANISM FOR SEWING MACHINES Charles W. Mueller, St. Louis, Mo., assignor to Lewis Invisible Stitch Machine Company, St.

Louis, Mo., a corporation of Maine Application March 24,

v 4 Claims.

This invention relates to new and useful improvements in sewing machines generally, although more particularly to a top feeding mechanism thereof.

Heretofore, in blind stitch sewing machines of the type specified, the top feed dog has been mounted on the front end of a lever which is mounted on the main frame of the machine for sliding pivotal movements and is actuated by an eccentric cooperating with the rear end of the lever. In this construction the fulcrum point for the lever is fixed and consequently the feed 1 dog is given an elliptical l-motion movement in which the feeding stroke of the dog follows an arcuate path, and in which the up and down movement of the dog is variable in proportion to the throw of the eccentric. The throw of the eccentric has heretofore been changed either by substituting a different eccentric or by providing a radially adjustable eccentric. With this construction it has been found that when short feed strokes are imparted to the feed dog the up and down movement of the feed dog is correspondingly diminished and consequently the feed dog would not clear the fabric especially if a heavy fabric is being stitched. It has also been found in feed mechanisms of this type that when the feed travel of the feed dog has been considerably increased the up and down movement to the feed dog will be correspondingly increased and the feed dog in its upward movement will be moved to such an extent as to interfere with the looper which cooperates with the needle in the usual way in forming the chain stitches.

The principal object of this invention is to provide a 2-point adjustable fulcrum for the lever whereby the proper height of the feed dog will be obtained when the feed is set for either long or short stitches and whereby the feeding stroke of the dog will follow a straight or horizontal path whereby the material will be fed properly during each cycle.

With the above and other objects in view which will more fully appear, the nature of the invention will be more clearly understood by following the description, the appended claims, and the several views illustrated in the accompanying drawing.

In the drawing:

Figure 1 is an elevation of the left hand side of a frame arm showing the application of my invention thereto,

Figure 2 is a detail elevation of the right hand side of the arm,

1937, Serial No. 132,854

Figure 3 is a horizontal section taken on the line 3-3 of Figure 1,

Figure 4 is a horizontal section t line 4-4 of Figure 1,

Figure 5 is a vertical se 5--5 of Figure 1, and

Figure 6 is a perspective view of ing link.

aken-on the ction taken on the line the support-,-

ing parts throughout the drawing.

In the drawing, I have several figures of the shown my top feeding means mounted in a forwardly extending hollow frame arm 5. A main shaft 6 is journaled in the frame and has one end extending across the rear end of the arm. A horizontalpresser foot'Iwhich is attached to the front end of the arm is provided with a longitudinal feed slot 8. A top feeddog 9 which is located above the foot is f xedly secured to the front end of a feed lever I0, and is adapted to operate in the slot 8 of the foot to feed the fabric rearwardly. An adjustablethrow eccentric II is mounted on the main shaft 6 and. is ,operatively connected to the rear end of the feed lever II] in the usual manner, and inasmuch as the constructio well known, it is thought cally show or describe the n of this eccentric is unnecessary to specifisame. The major axis of the feed lever is disposed in a substantially horizontal plane.

Formed in the lever adjacent the forward end thereof are front and rear pivot openings I2 and I3 respectively, and formed in the adjacent side wall l4 of the arm 5 below said openings are front and rear bearing openings I5 and I6 respectively, the distance between the centers of openings I2, I3 being the same as the distance between the centers ofopenings I5, I6. Bushings- II, I8 are mounted in the and formed in the wall I4 frame openings I5, I6, of the arm 5 above said openings I5, I6 is a longitudinal and substantially horizontal slot I9. A vertical supporting link 20 is provided for the lever I vided at its lower end W1 0, and this link is proth a threaded opening 2| and at its upper end with an elongated nonthreaded and laterally which projects into the slot 5. A shouldered bearing be positioned in extending bearing 22 I9 of the frame arm screw 23 is adapted to either one of the bushings IT or I8 and has its reduced end 24 threadably engaged ably engaged in one or the I2 or I3 of the feed lever of the link. A shouldered pivot d in the extended bearing 22 educed end 215 threadother of the openings II]. A flange 21 which is integral with the upper end of the link, projects upwardly from the link and includes rearwardly and forwardly extending wings 28, 29 respectively for receiving oil from tubes 5 mounted in the arm 5, the oil thence gravitating to the pivot screw 25 and to the bearing screw 23.

When it is desired to form long stitches, say from two to five stitches to the inch, the link 20 is positioned as shown, that is, with the bearing screw 23 engaged in the bushing I! of the front opening l5 and with the pivot screw 25 engaged in the front opening l2 of the feed lever.

When it is desired to form short stitchessay from six to twelve stitches to, the inch, the link 20 is moved rearwardly after first disconnecting. the bearing screw 23 from the link and thelpivotscrew 25 from the feed lever, and thebearing screw 23 is then engaged in the bushing iii of the rear bearing opening I6 of the frame arm, and the pivot screw 25 is then engaged in the rear opening l3 of the feed lever.

In operation, itis necessary during the feeding stroke of the feed dog, for the dog to travel in a definite plane below the bottom of the foot, the distance being approximately g inch. This distance must be maintained, regardless of the length of'the feed travel, in order to engage properly the fabric which is being fed under the stationary foot. Thus this condition is present when forming long stitches and with the link in its forward position as shown in Figure 1, but should the eccentric ll be adjusted to form short stitches, then the height of the feed lift would be lessened and the differential would be split at the top and bottom of the lift, and consequently the feed dog will have its feeding stroke in a plane above the desired horizontal plane which, as above stated, is approximately 3 2* inch below the foot. 'However, by shifting the link to its rear position, the feed dog lift will be increased and therefore short stitches can be made and the plane of travel. of the dog during its feeding stroke will be at the desired distance below the foot.

It will thus be seen that I have provided a 4- motion top feeding mechanism wherein both the feed travel and the feed lift are imparted to the feed dog by theadjustable eccentric H, the feed lever l0, and the supporting link 20. 7

It is of course to be understood that the details of structure and arrangement of parts may be variously changed and modified without departing from the spirt and scope of my invention.

I claim:-

1. A 4-motion top feed mechanism for sewing machines comprising a frame arm, a drive shaft extending across the rear end of the arm, a feed lever extending longitudinally of the arm, an adjustable eccentric fixed to the shaft and havlever extending longitudinally of the arm and provided intermediate its ends with front and rear spaced pivot openingsthe frame arm being provided with spaced front and rear bearing openings, an adjustable eccentric fixed to the shaft and having operative connection with the rear endof the lever; a feed dog mounted on the front end of the lever, and a vertically disposed supporting link between the lever and the arm ;,and adapted to have operative connection with the front opening of the lever and the front bearing opening of the arm, or with the rear opening of the lever and the rear opening of the arm.

3. A 4-mo'tion to-p feed mechanism for sewing machines comprising a frame arm, a drive shaft extending across the rear end of the arm, a feed lever extending longitudinally of the arm and provided intermediate its ends with front and rear spaced ,pivot openings, the frame arm being provided with spaced front and rear bearing openings and with a longitudinal slot above the openings, an adjustable eccentric fixed to the shaft and having operative connection with the rear end of the lever, a feed dog mounted on the front end of the lever, a vertically disposed supporting link adapted to have its lower endfulcrumed in one of the bearing openings in the arm and provided at its upper end with an extended bearing projecting into the longitudinal slot of the arm, and a pivot screw journaled in said extended bearing and adapted; to have threadable engagement with one of the pivot openings ofthe lever.

4. A 4-motiontop feedme'chanism for sewing machines, comprising a hollow frame arm having a longitudinal wall provided with a longitudinally extending slot and with a'bearing opening below the slot, 2. drive shaftextending across the rear end of said arm, a feed lever extending longitudi- I nally within the arm and having driving connections at its rear end with said shaft, a feed dog mounted on the front end of the lever, a vertically disposed supporting link fulcrumed in said bearing opening and having an extended bearing projecting from its upper end into said slot, and a pivot screw journaled in said extended bearing and having threadable engagement with said lever intermediate the ends thereof.

CHARLES W. MUELLER. 

